Horrendously ineffective safety cage. You shouldn't be able to get fingers that close to the mill nip. It's an accident waiting to happen. Using a Stanley knife on the mill causes scoring of the mill bole. We always used a piece of machine saw blade wrapped in rubber for handle and sharpened to concave . With a slightly rounded tip it didn't damage the mill.
I ran a 60” mill for many years making rubber products and Viton. We used to have three layers of safety. A kick plate, a laser screen, and a manual brake. Always using loose cotton gloves.